1. Field of the Invention
The present invention relates to a mobile communication system which transfers, based on address information of a mobile communication terminal, a packet addressed to the mobile communication terminal which forms an adhoc network, through a core network.
The present invention also relates to a mobile communication terminal used in the mobile communication system.
2. Description of the Related Art
FIG. 1 is a diagram showing a whole configuration of a mobile communication system. In the mobile communication system, based on address information of the mobile communication terminals MT#1 to MT3, a packet is addressed and transferred to mobile communication terminals MT#1 to MT#3 which form an adhoc network A, through a core network CN.
Conventionally, “Globalv6[1]” has been proposed as the mobile communication system described above.
In this mobile communication system, each of mobile communication terminals MT manages a home address HoA and a care-of address CoA of the terminal itself, as the address information.
In the mobile communication system, packets are configured to be sent to each of the mobile communication terminals MT based on the home address HoA and the care-of address CoA in communications through a core network.
In the mobile communication system, packets are configured to be transferred to each of the mobile communication terminals MT based on the home address HoA or the care-of address CoA in communications through an adhoc network.
To be more specific, each of the mobile communication terminals MT is configured to transfer packets to other mobile communication terminals MT, in accordance with a routing table which associates a “destination address” with a “next hop”, in routing processing within the adhoc network.
In FIG. 1, a routing table stored in a mobile communication terminal MT#3 is shown as a representative of the mobile communication terminals MT within the adhoc network A. Here, both routing addresses before and after the mobile communication terminal MT has been moved are shown.
The care-of address CoA of each of the mobile communication terminals MT includes a prefix and a terminal number. The prefix is assigned by an access node AN connected to the adhoc network to which the mobile communication terminal MT belongs. The terminal number is unique within the adhoc network.
In FIG. 1, when the adhoc network A which is formed by the mobile communication terminals MT#1 to MT#3 is connected to an access node AN1, a care-of address of the mobile communication terminal MT#1 is “AN1prefix#1” including a prefix “AN1prefix” which is assigned by the access node AN1 and a terminal number “#1”, a care-of address of the mobile communication terminal MT#2 is “AN1prefix#2” including the above described prefix “AN1prefix” and a terminal number “#2”, and a care-of address of the mobile communication terminal MT#3 is “AN1prefix#3” including the above described prefix “AN1prefix” and a terminal number “#3”.
However, in the aforementioned mobile communication system, there has been a problem in that, when a handoff occurs while the adhoc network A is formed by the mobile communication terminals MTs, or more specifically, when any one of the mobile communication terminals MT forming the adhoc network A moves, and a connection point between the adhoc network A and the core network CN accordingly is changed from the access node AN1 to another access node AN2, since a care-of address CoA of each of the mobile communication terminals MT is changed, a large amount of recalculation is required to be performed in each of the mobile communication terminals in order to reconstruct a routing table, irrespective of whether topology within the adhoc network A is changed or not.